July, 1915. 
The Queensland Naturalist. 
9 
to scrutiny and criticism. Theories must be fully tested 
to see whether they accord with facts. Hypotheses must 
be demonstrated by experiment. The great and only 
criterion for workers should be, “ Is it true ? ” And science, 
with ever-widening knowledge, with the results of life-labours 
of a multitude of specialists, armed with new powers of 
observation and research, such as are to be found in present 
day laboratories, has come to widen her theories of evolution. 
Let us try to exemplify by two or three statements the 
positions of modern thinkers as compared with those of, 
sav, 30 years ago. One may be epitomised in the words of 
Bateson; 0) “No one can survey the work of recent years 
without perceiving that evolutionary orthodoxy developed 
too fast, and that a great deal has got to come down." 
Another is a recognition that sweeping conclusions are not 
always justified from a set of observations, and that 
generalisations whidi may govern the history of certain 
organisms may not be universal, and it is thus incorrect to 
project them through the wliole realm of phenomena. Let 
me illustrate this by a reference to Mendelism. The Mendelic 
laws undoubtedly hold good in many cases, but they are 
notoriously contradicted or superseded in others, as a study 
of mulattoes, half-castes, hybrids, and mixed offspring reveals. 
Nor does the concomitant acceptance of what Mendelians 
call “ independent inheritance ’’ satisfy the critics. The 
supposed universality of the Mendelic principle has been 
largely suggested by focussing attention on certain points, 
and ignoring others. Heredity is more often a complex 
synthesis than a mosaic of dominants and recessives. 
To my mind, the third, and perhaps the greatest 
distinction of manv present-day workers, is their critical 
attitude towards teleology— or the doctrine of purposiveness 
in nature. Here we have varying schools, and a fierce, 
and not always courteous, controversy is raging in some of 
our scientific journals between their exponents. A brief 
review of the concepts of two leaders. Loeb and Bergson, 
will outline their standpoints. 
Much of the work done by Loeb and by those associated 
with liim is now well known. The experiments with sea- 
urchins are, perhaps, of the greatest interest. By raising 
the alkalinity of seawater Loeb and others are able to fertilise 
the eggs of sea-urchins with sperm of widely different groups, 
such as holothurians, brittle stars, and even molluscs, and 
heterogeneous hybrids are thus created. Variation and the 
life-form itself are apparently at the disposal of chemical 
processes. To quote Loeb’s own words : “ We know that 
growth and development in plants and animals are determined 
by definite although complicated series of catenary chemical 
(1( “Darwin and Modern Scienc#*.’* p. 101. 
